Dixon mower lemon

I bought a dixon ram 44 mag from a guy I knew, turned out to be a terrible deal. The mower is a ram 44 mag with great paint and runs well. He said there was deck trouble... well he was right. I changed a few bearings and installed new blades. When I got it the deck was off. I now have realized that he sold me a ram 44 mag mower with a deck off of a older 44" dixon mower. It fits and everything, the only trouble I have is that the drive belt throws all the time. Like a few times a minute. What should i Look for to get it aligned properly? Also it doesnt seem like the springs on the 2 arms that go from the deck to under the mower have enough pressure. Is that really all there is to keep the belt on? There is no adjustment? Also how easily should the deck belt turn? I can turn it with my hands without straining myself but it has a little pressure to it. Could that be the problem? If i put the belt on it turns ok just throws itself. Is there a source out there where I could get a deck that is for that mower, like a mower graveyard?

Sounds very much like it needs a shorter belt.
Get some rope the same diameter as the belt 1/2" or 5/8" .
Route it around the engine & deck so that the tension arm is about 1/3 way on its travel ( remove the spring to do this ) .
Double check this with the spring sitting loose on the deck.
Measure the length of the rope and that is the size belt you need.
In those sizes they come in 1" incriments just make sure you buy a Kevlar mower belt .
You can try a standard V belt first to make sure of the length as they are about 1/3 the price